A review of the current state of knowledge on the effects of radiation on concrete in nuclear power production applications is presented. Emphasis is placed on the effects of radiation damage, as reflected by changes in engineering properties of concrete, in the evaluation of the long-term operation and for plant life or aging management of nuclear power plants (NPPs) in Japan, Spain, and the United States. National issues and concerns are described for Japan and the United States followed by a discussion of the fundamental understanding of the effects of radiation on concrete. Specifically, the effects of temperature, moisture content, and irradiation on ordinary Portland cement paste and the role of temperature and neutron energy spectra on radiation-induced volumetric expansion (RIVE) of aggregate-forming minerals are described. This is followed by a discussion of the bounding conditions for extended operation; the significance of accelerated irradiation conditions; the role of temperature and creep; and how these issues are being incorporated into numerical and meso-scale models. From these insights on radiation damage, analyses of these effects on concrete structures are reviewed, and the current status of work in Japan and the United States is described. Also discussed is the recent formation of a new international scientific and technical organization, the International Committee on Irradiated Concrete, to provide a forum for timely information exchanges among organizations pursuing the identification, quantification, and modeling of the effects of radiation on concrete in commercial nuclear applications. The paper concludes with a discussion of research gaps, including (1) interpreting test-reactor data, (2) evaluating service-irradiated concrete for aging management and to inform radiation damage models with the Zorita NPP (Spain) serving as the first comprehensive test case, (3) irradiated-assisted alkali-silica reactions, and (4) RIVE under constrained conditions.
In the Hokuriku district in Japan, large numbers of concrete structures have been suffering from damage caused by alkali silica reaction (ASR). Some huge volcanoes are located within this district, and the headwaters of main rivers prompt the outflow and spreading of volcanic rocks such as andesite, rhyolite and tuff stones, which are the main volcanic reactive stones causing the serious damage of ASR in the entire area. To solve this problem effective countermeasures such as repair and strengthening methods should be established.
One intake tower in this area had deteriorated due to ASR, and deformation had occurred as a consequence of ASR ex-pansion of the concrete. Countermeasures were carefully considered by academic experts, and post-tensioned tendons were inserted into the intake tower concrete (vertically oriented) so that the power station can continue to operate safely in the future. This is thought to be the first challenge of its type anywhere in the world for which the deformation of a real structure caused by ASR expansion must be controlled.
In this paper, the results obtained from laboratory tests using reactive aggregate and the overview of the investigation and the method of the reinforcement including the effect of the countermeasures will be discussed.